Photonic networks provided with a reconfigurable optical add-drop multiplexer and/or a wavelength cross connect have been proposed and developed. A reconfigurable optical add-drop multiplexer (ROADM) is capable of dropping an optical signal of a desired wavelength from a WDM (Wavelength Division Multiplexing) signal so as to guide the signal to a client and of adding a client signal of an arbitrary wavelength to a WDM signal. A wavelength cross connect (WXC or PXC: Photonic Cross Connect) is capable of controlling routes of optical signals for each wavelength without converting these signals into electric signals.
In a photonic network as described above, a plurality of optical paths (wavelength paths) that use the same wavelength are sometimes set. Accordingly, in order to construct and operate networks reliably, a method for example in which path IDs for identifying respective optical paths are superimposed on an optical signal to be transmitted is proposed. In such a case, node devices (reconfigurable optical add-drop multiplexers, wavelength cross connects, etc., in this example) in a photonic network are provided with a function of detecting a path ID superimposed on an optical signal. This enables secure identification of each optical path in a node device, making it possible to monitor, detect, and avoid failures such as connection of an optical fiber to a wrong port.
As a technique of managing optical paths, a method including the following processes is proposed. Specifically, at least one sub data stream is coupled with at least one payload data stream so as to generate a synthetic-electricity data stream. The synthetic-electricity data stream is supplied to an optical modulator so as to generate an optical signal. An optical receiver having an operation frequency lower than the half the speed of the synthetic-electricity data stream detects the optical signal. Then, the sub data stream is restored from the electric output of the optical receiver.
As related techniques, U.S. Pat. No. 7,580,632, U.S. Pat. No. 7,512,342, U.S. Patent Publication No. 2009/0169210, U.S. Patent Publication No. 2010/0080568, Japanese Laid-open Patent Publication No. 11-331224, Japanese Laid-open Patent Publication No. 2008-263590, and Vinay A. Vaishampayan and Mark D. Feuer, “An Overlay Architecture for Managing Lightpaths in Optically Routed Networks,” IEEE Transactions on Communications, Vol. 53, No. 10, October 2005 are known.